Numerous devices have been conceived for placing between adjacent boards and/or sheets of lumber products. Such devices are meant to separate the boards between which they are positioned for promoting better drying of wood in a kiln, among other reasons. Such separators, sometimes called “stickers”, also enhance airflow between stacks of materials that have already been kiln dried. Preferred separator/sticker devices are made from materials that will minimize the possibility of leaving residual marks on the products they are used to separate for a given time.
In Hutcheson U.S. Pat. No. 3,907,130, there is disclosed a kiln sticker, or “crosser”, with generally crescent-shaped, top and bottom load bearing surfaces for lumber separation. The top surface 16 to the sticker at FIG. 4 has a flattened crest. Some air passage is provided with the inverted V-shape base to each sticker/crosser.
In Davis U.S. Pat. No. 4,788,777, the respective stickers are shown as elongated hollow extrusions, preferably made from a synthetic resin with fiberglass reinforcement. While these stickers may have the various cross-sectional shapes shown in FIGS. 2 through 4, none of these shapes provide airflow through or about the stickers themselves.
Menchetti et al., U.S. Pat. No. 5,722,626 discloses separating stacks of product with reusable devices. The wavy risers shown in FIGS. 2 and 3 can be made from recycled wood chips, plastic and/or gypsum. For better reinforcement between layers, alternate embodiments like those in FIGS. 9 through 11, include intermediate strengtheners. None of these riser designs provide for air passage through same, or from side-to-side.
Townsend, U.S. Pat. No. 5,813,137, discloses a modified separator, with transverse grooves, for use in separating pieces of lumber. These separators are distinguishable, though, by their sharply peaked ridges or protrusions and broader grooves in between—which limit surface contact between the separators and stacked lumber. However, this limitation on surface contact can cause warping in the separated lumber. In addition, when wood separators are used with the Townsend separator, the separated wood can be damaged by staining resulting from wood wicking or soaking, i.e., the peaked ridges or protrusions leave a mark on the separated wood.
The flexible wood stickers of Gilchrist et al., U.S. Pat. No. 6,134,803 are made from high molecular weight polyethylene. At the ends, these stickers have an X-shaped cross-section with rounded edges. But at various longitudinal points, each sticker has an inclined, cut groove leading to the helical configuration of FIGS. 3 through 7 when rotated 90, 180 and 270 degrees about its central axis.
The present invention represents an improvement over the lumber sticker of commonly owned U.S. Pat. No. 7,003,898. That prior configuration included elongated, generally rectangular-shaped blocks with a series of diagonal channels and platforms along their top and bottom surfaces. Preferred embodiments included arcuate side surfaces for precluding lumber from resting on either side when stacked between adjoining lumber layers.